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Effective temperature scale and bolometric corrections from 2MASS photometry
We present a method to determine effective temperatures, angularsemi-diameters and bolometric corrections for population I and II FGKtype stars based on V and 2MASS IR photometry. Accurate calibration isaccomplished by using a sample of solar analogues, whose averagetemperature is assumed to be equal to the solar effective temperature of5777 K. By taking into account all possible sources of error we estimateassociated uncertainties to better than 1% in effective temperature andin the range 1.0-2.5% in angular semi-diameter for unreddened stars.Comparison of our new temperatures with other determinations extractedfrom the literature indicates, in general, remarkably good agreement.These results suggest that the effective temperaure scale of FGK starsis currently established with an accuracy better than 0.5%-1%. Theapplication of the method to a sample of 10 999 dwarfs in the Hipparcoscatalogue allows us to define temperature and bolometric correction (Kband) calibrations as a function of (V-K), [m/H] and log g. Bolometriccorrections in the V and K bands as a function of T_eff, [m/H] and log gare also given. We provide effective temperatures, angularsemi-diameters, radii and bolometric corrections in the V and K bandsfor the 10 999 FGK stars in our sample with the correspondinguncertainties.
| The 1000 Brightest HIPASS Galaxies: Newly Cataloged Galaxies
The H I Parkes All-Sky Survey (HIPASS) is a blind 21 cm survey forextragalactic neutral hydrogen, covering the whole southern sky. TheHIPASS Bright Galaxy Catalog (BGC) is a subset of HIPASS and containsthe 1000 H I-brightest (peak flux density) galaxies. Here we present the138 HIPASS BGC galaxies that had no redshift measured prior to theParkes multibeam H I surveys. Of the 138 galaxies, 87 are newlycataloged. Newly cataloged is defined as having no optical (or infrared)counterpart in the NASA/IPAC Extragalactic Database. Using the DigitizedSky Survey, we identify optical counterparts for almost half of thenewly cataloged galaxies, which are typically of irregular or Magellanicmorphological type. Several H I sources appear to be associated withcompact groups or pairs of galaxies rather than an individual galaxy.The majority (57) of the newly cataloged galaxies lie within 10° ofthe Galactic plane and are missing from optical surveys as a result ofconfusion with stars or dust extinction. This sample also includes newlycataloged galaxies first discovered by Henning et al. in the H I shallowsurvey of the zone of avoidance. The other 30 newly cataloged galaxiesescaped detection because of their low surface brightness or opticalcompactness. Only one of these, HIPASS J0546-68, has no obvious opticalcounterpart, as it is obscured by the Large Magellanic Cloud. We findthat the newly cataloged galaxies with |b|>10° are generally lowerin H I mass and narrower in velocity width compared with the totalHIPASS BGC. In contrast, newly cataloged galaxies behind the Milky Wayare found to be statistically similar to the entire HIPASS BGC. Inaddition to these galaxies, the HIPASS BGC contains four previouslyunknown H I clouds.
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Osservazione e dati astrometrici
| Costellazione: | Dorado |
| Ascensione retta: | 04h47m22.16s |
| Declinazione: | -57°08'57.3" |
| Magnitudine apparente: | 9.319 |
| Moto proprio RA: | 8.7 |
| Moto proprio Dec: | 3.9 |
| B-T magnitude: | 9.751 |
| V-T magnitude: | 9.355 |
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